Nuclear radiation absorbing glass

ABSTRACT

In a glass composition containing boric acid as the glass former and further containing the oxides of beryllium and lithium for the purpose of slowing down and moderating nuclear radiation a certain percentage of tungsten oxide is introduced to the effect that the percentage of lithium oxide can then be increased to an amount which in pure L:20/BeO/B2O=3-glasses has previously only been achieved with miniature melts of approximately 0.5 grams.

United States Patent Inventors Heinz Bromer Hermannsteln/Km Wetzlar; Norbert Melnert, Wetzlar; l-lans-Jorgen Preuss, Wetzlar, all of Germany Appl. No. 755,550

Filed Aug. 27, 1968 Patented Nov. 9, 1971 Assignee Ernst Leltz Gmbll Wetzlar, Germany Priority Aug. 29, 1967 Germany L 57316 Vlb/32b NUCLEAR RADIATION ABSORBING GLASS lmadka Glass Formation Range and Glass Structure" Advances in Glass Technology- Plenum Press NYC 1962 pp. 149- 164, page 152 relied upon Primary Examiner-Helen M. McCarthy Auurney-Krafft & Wells ABSTRACT: In a glass composition containing boric acid as the glass former and further containing the oxides of beryllium and lithium for the purpose of slowing down and moderating nuclear radiation at certain percentage of tungsten oxide is introduced to the effect that the percentage ol'lithium oxide can then be increased to an amount which in pure L:,0/BeO/B,O- -,-glasses has previously only been achieved with miniature melts of approximately 0.5 grams.

BACKGROUND OF THE INVENTION 2 accordingto the'invention, numbered 1, 2 and 3 in the below provided'table. Further, the diagram outlinesalso the transmission of-tungsten-free glass and of paraffin.

1 Field of the invention 5 DESCRIPTION or'rmz PREFERRED EMBODIMENTS The present invention relates to glass having theproperty of absorbing nuclear radiation, which glassmay thus beused as a The glasses comm! the comm generally of nuclear radiation shield in atomic research laboratories and l t l-26l by wt. or -45 IIlOl In 1.1.0

2 Description of the Prior-Art 10 8: :3 3:1, z 2:: and

In the field of atomlc research-1t 1s already known that ele- 147 a, by wt. or 0.2411101 '71 W0, ments of low atomic weight are especially suitable for slowing down and moderating fast neutrons; Thusyfor the'viewing win- To these compositions may be added up to 5 percent by wt. dows in atomic plants and laboratories glasses havexalready (or 2mol-percent Sm',0', andin the following table sevendifbeen suggested which consist essentially of the oxidesoflithiferent glass composition are listed which are composed-acum and beryllium and of boric acid asthe glass'former. cording to the above stated general rule:

TABLE 1 Liz() B00 ":0; Wm Silk-()3 Molec- Molvc- MOltU- 1\l0l1 0- M01110 ll-romit ular Percent ulm' lvrcmil. ulul l't lctlll ul=1r I'm-c0111. ular by p0rby {)(P by porby pm by p01- weight cant weight cont wvight cent weight cent wright cent Glass NO.:

1... 17.7 31.8 3.11 3.4 77.0 511.5 1.4 0.3 2. 16.3 31.2 3. 0 :42 71.0 58.3 0.1 2.3 3. 24.1 43.5 7.4 14. 7 01.1 40.2 7.4 1. 0 4. 10.7 33.5 3. 3 7. 0 03. 3 54.3 16.7 4.3 5.. 15.2 27, 3 8.1 17. x 66. 0 51. s 10. 7 2. 0 6.. 15.8 31.0 3.5 3.2 03.4 57. 7 12.3 3.1 7... 15.4 30.0 3.4 s1 66.6 57.4 12.0 v 3.1 2.11 0.5

The boron also having the additional task of capturing the Now, it has been discovered that the moderator effect of neutrons after the latter have been slowed down to the therthese glasses practically compares to the moderator effect of mal region. Classes of this nature have already been corresponding tungsten-free glasses. For example, the glass described, for example, in the US. Pat. No. 2,747,105 and in types listed under No. l and 2 of the foregoing table corthe ".loumal of the Society of Glass Technology" (Great respond toatungsten-free'glass of the following composition: Britain), Volume XL 1956, page 66T. Li, 0=l 8 by wt.

However since capturing of the neutrons by the boron is Be0=4 by wt. only possible after the neutrons have been-sloweddowntothe 40 B, 0 =78 '11 by wt. Further, it is an additional advantage thermal region considerably thick glass plates are required in that the glasses according to the invention absorb the the above-mentioned viewing windows if they are to protect gamma di i hi h occurs besidgs h l [adiathe Viewers e fe ti lytion to a considerably higher degree than do the tungsten The main disadvantage in the composition of these known ffee,glms A eag e f r hi i id d b h ffiglass types resides in the fact that lithium oxide as well as cient of absorption which is listed below for three types beryllium oxide are soluble in boric acid only toa limited exf h glasses according to h invention f 60 g m tenL A Certain increase of ihc p l beryllium Oxide is radiation along with the coefficient for para'ffin and tungindeed possible if additional portions of aluminum oxide are ten f ee l contained in these glasses, however, a marked reduction of the thickness of the glass plates cannot be achieved this way,if full Farm protection of the operators viewing through the windows is to tungstemfree .1 0.111 cm. b i i d example l (H 14 cm."

example 3 (I I2] cm." SUMMARY OF THE INVENTION 1 Y Now, it has been discovered that by adding tungsten oxide With the gamma radiation which results from the capture of to the glass composition the percentage of lithium oxide in slow neutrons by the boron which is the case in 93 percent these glasses can be increased to an amount which in pure the differences are even substantially greater. Li,O/BeO/B0,-glasses can be achieved only in miniature The glasses according to the invention are particularly inmelts of approximately 0.5 grams. Moreover, adding tungsten teresting with regard to their optical properties owing to their oxide has the advantage that tungsten itself is already capable unusual partial dispersion. These values are set forth in the of capturing neutrons having energies in the epithermal retable below: gion. As a consequence thereof, it is possible safely to reduce the thickness of the protective shields up to one third. The ef- TABLE 3 feet of the tungsten can even be increased if to the glasses 5 Glass No. 11. vn 110 Av.- other of elementsare added which are capable of capturing Tungsmbrm 1,564; 63,6 4677 !1.0 neutrons in the epithermal region as, for example, the oxlde of Example: samarium. The addition of the oxides of tungsten and samari- :2; um has the advantage that the fields of high absorption ranges a: 115715 59: 1 4743 -7I7 superimpose and complement each other in the epithermal re- M732 gion.

All of the glasses according to the invention can be melted DESCRIPTION OF THE APPENDING DIAGRAM in conventional manner as is outlined below for one particular In the diagram is illustrated the transmission of fast neutrons example concerning the melting process of a 500 gram batch;

composition.

in dependence on the glass thickness of three different glasses The well mixed batch is in portions put into the melting furnace at a temperature of 1 100C, subsequently melted for minutes at l200 c, and then stirred and cooled down to 950 The melt is cast into aluminurnrnolds preheated to What is claimed is: 1. A nuclear radiation absorbing glass composition consisting essentially of:

Li,0 BeO I: by weight I5. 24.1 about 3.3 to SJ about 6l-77 about L410 I647 g up to about 26 percent UNITED STATES PATENT OFFICE PAGE ONE CERTIFICATE OF CORRECTION Patent No. 3, 619, 219 Dated November 1 71 n (s)HEINZ BR CMER: NORBERT MEINERT: & HANS-JURGEN PREUSS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Block [72[, line 1,"Bromer" should read Brb'mer- Block |72|, line 3, "Hans-Jorgen" should read Hans-Jurgen- Block |56| line 9, "Imadka" should read Imaoka- Abstract, lines 6 and 7, "pure L: O/BeO/B glasses" should read pure Li O/BeO/B glasses- Column 1, line 59, "Li O/BeO/]3O glasses should read -L1 O/BeO/B O -glasses Column 2, line 14, (or 2 mol percent Sm O and" should read (or 2 mol percent) Sm O and- Column 2, line 15, glass composition" should read glass compositions- Column 2, line 40, "B 0 78%" should read -B o 78% Column 2, line 46, "invention of SO gamma" should read invention of 60 Co gamma- )RM Po-1050 (10-69) uscoMM-Dc 60375-969 US, GOVERNMENTPRINTING OFFICE 1959 0-3654.

UNITED STATES PATENT OFFICE Page Two CERTIFICATE OF CORRECTION Patent 3.619.219 Dated November 9 1971 H Inventor(s) HEINZ BROMER: NORBERT MEINEBT: 81 HANS-JURGEN PREU SS It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 50, "cm" should read -cm Column 2, l in e;5 1, "cm" should read --cm Column 2, l ir 5 2, "cm" should read cm Column 2, line 53, "cm" should read -m' Column 2, line 54, "cm" should read cm Column 2, line 57, "(which is the case in 93 percent" should read -(Which is the case in 93 percent) Column 2, l ir e 'l4, of a 500 gram batch;' should read -of a 500 gram batch- Claim 2, line 2, "about 26 percent" should read -about 2. 6 percent- Signed and sealed this 20th day of March 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents RM powso USCOMM-DC scan-ps9 U.S GOVENNHENT PRINYING OFFICE: 196! D36G-334 

2. A nuclear radiation absorbing glass composition according to claim 1, and further containing up to about 2.6 percent by weight of the oxide of samarium. 